High-energy propellant oxidizer and method for synthesis



United States Patent 3,350,440 HIGH-ENERGY PROPELLANT OXIDIZER AND METHOD FOR SYNTHESIS Perry A. Argabright, Cranford, and Lawrence J. Engel, Duneilen, N.J., assignors to Esso Research and Enginearing Company, a corporation of Delaware No Drawing. Filed Dec. 11, 1961, Ser. No. 159,478 3 Claims. (Cl. 260490) HHHEI) H2C=C l( J-O O OH; This diolefinic acetate is a known available material which may be obtained by reaction of ketene, CH =CO, with crotonaldehyde, CH CH=CHCHO.

After initial efforts to make the tetrakis-(NF adduct of the acetoxybutadiene had failed, the tetrakis-(NF adduct desired was unexpectedly achieved by use of the method which will be described. In the initial eiforts to react the butadiene acetate with N F it appeared that only certain bis-(NF adducts could be obtained. However, it was then found, in accordance with the present invention, that by removing decomposition products of N F formed at higher temperatures and then by recharging with fresh N F the reaction could be made to proceed to complete conversion to the tetrakis adduct which may be termed tetrakis-(difluoramino)-butylacetate or tetrakis-(difiuoramino)-1-acetoxybutane.

Two varieties of procedure for preparing the tetrakis- (NF derivative of 1-acetoxy-1,3-butadiene were used. In the first of these, the bis-(NF adduct is formed in an initial vapor-phase reaction stage, after which the his adduct from the first stage is subjected to reaction with fresh N F under increased pressure and with liquid diluent.

In the second procedure, the l-acetoxy-LB-butadiene reactant is subjected to reaction with N F under high pressure in the presence of liquid diluent at the beginning, then the reaction temperature is increased and fresh N E is charged to replace decomposition products of the initial N F charge.

By using the mode of procedure in which a vapor-phase reaction is conducted as a first stage, there is the advantage of employing steps that increase the rate of reaction in a homogeneous vapor-phase system, and a continuous flowtype reaction may be used. The second mode of procedure has the advantage of using a single reaction zone or single reactor, such as a stainless steel pressure bomb, and in using higher concentrations of reactants from the beginning of the reaction. To control the reaction so as to avoid hazard of explosion, the beginning of the reaction toward the formation of bis-(NF adduct is made to take place at a low temperature, such as 20 C. or room temperature, or in the range of 50 to +100 C. After this initial phase of reaction in which the his adduct is formed, the reaction is made to take place under superatmospheric pressure, e.g. about 1 to atmospheres or higher, and at temperatures in the range of about 50 to 250 C. The preferred conditions of reaction are set forth in the following examples on each of the two modes of procedure.

EXAMPLE 1 For the procedure in which an initial vapor-phase reaction is carried out, the acetoxybutadiene is mixed in vapor phase with gaseous N F to form a mixture having a subatmospheric pressure at 25 C. The acetoxybutadiene reactant is preferably in a proportion of 1 mole to 2 moles of N F If no inert gas is admixed, a higher proportion of N F is used. With inert gas present, the proportion of N F to the acetoxybutadiene may be lowered for producing the his adduct at a reasonable rate. The bis adduct has a composition of approximately C H O (NF The bis-(NF adduct product from the vapor-phase stage is then reacted further in a higher pressure stage with an increased proportion of N F e.g. 3 moles of N F per 1 mole of the his adduct, with dilution by a diluent such as CCL, or other suitable halocarbon liquids. This mixture is then heated to a temperature of 50 to 250 C. at a pressure of 450 p.s.i.g. in a stainless steel pressure bomb for a suitable period, depending on the temperature, e.g. a period of 1.5 to 15 hours or, more particularly, C. for 7 hours, with mixing. In this pressure stage, the removal of the N F and partially decomposed N P gaseous a composition close to of C H O (NF- If the reaction is not carsufiiciently high temperature and pressure with and for a suflicient the theory ried out at procedure in which pressure is used pressure reactor is described in the fol- EXAMPLE 2 The starting material was placed in the stainless steel pressure reactor with gaseous N F and CCL; liquid diluent. Sufficient N F was supplied to make the pressure in the reactor 450 p.s.i.g. at 150 C. The reaction mixture C, 22.50%; N, N, 17.30%; F,

The mode of throughout in a lowing example.

unreacted N F and degradation products thereof were removed and replaced by fresh N F gas to obtain complete conversion to the desired tetrakis- (NF -butylacetate. This tetrakis product, after being fractionally distilled, was analyzed and found to have the composition 6 H O (NF and structure of 1,2,3,4-tetrakis-(NF )-l-acetoxybutane or which has been termed tetrakis-(NF )-butylacetate.

The tetrakis-(NF )-butylacetate product has been determined to have high energy in compounding with fuel ingredients, with other oxidizing ingredients, and binders suitable for making a solid rocket propellant grain having an Isp. in the range of 270-290. This is exemplified by the following formulation:

Propellant composition Ingredient: Wt. percent C H O (NF 20 Boron powder 9 C (NO 51 Polybutadiene-NF adduct binder 20 The C H O (NF represents the tetrakis-(NF )-butylacetate as fluorine oxidizer which furnishes fluorine for oxidizing the powdered fuel and some of the hydrogens. The C (NO is hexanitroethane used as oxygen oxidizer which supplies oxygen for oxidizing carbon and which may also supply oxygen to convert the boron fuel to BOP. The polybutadiene-(NF adduct binder in the present instance is polymer having the composition of the recurring unit C4H6(NF3)1 7. The resulting solid mixture has been determined to have a combustion temperature of 4300 C. and an Isp. value of 284 seconds. The

2. Process for the synthesis of tetrakis-(NFQ-butylacetate which comprises reacting 1-acetoxy-1,3-butadiene in vapor phase with sufficient N F under subatmospheric pressure at a temperature in the range of 20 to 100 C. to form a bis-(N1 adduct of the acetoxy-1,3-butadiene, reacting the resulting bis-(NE) adduct of the acetoxybutadiene with a fresh charge of N F at a temperature in the range of to 250 C. under superatmospheric pressure in the presence of an inert halocarbon diluent to convert the bis-(NF adduct to tetrakis-(NF -butylacetate product, and recovering said product.

3. Process for the preparation of tetrakis-(NF )-butylacetate which comprises forming a mixture of N F under superatmospheric pressure of about 1 to 10 atmospheres with 1-acetoxy-l,3-butadiene diluted with liquid CCl heating the resulting mixture under pressure to a temperature in the range of to 250 C., removing gaseous degradation products from the resulting mixture and charging fresh N F to the resulting mixture for further heating of said mixture with the fresh charge of N 1 under superatmospheric pressure to a temperature in the range of 100 to 250 C. to produce tetrakis-(NF -butylacetate, and recovering the resulting tetrakis- (NF -butylacetate product.

LORRAINE A. WEINBERGER, Primary Examiner. L. D. ROSDOL, O. R. VERTIZ, Examiners. J. W. WHISLER, V. GARNER, Assistant Examiners. 

1. TETRAKIS-(DIFLUORAMINO)-BUTYLACETATE HAVING THE COMPOSITION C6H8O2(NF2)4.
 2. PROCESS FOR THE SYNTHESIS OF TETRAKIS-(NF2)-BUTYLACETATE WHICH COMPRISES REACTING 1-ACETOXY-1,3-BUTADIENE IN VAPOR PHASE WITH SUFFICIENT N2F4 UNDER SUBATMOSPHERIC PRESSURE AT A TEMPERATURE IN THE RANGE OF 20* TO 100*C. TO FORM A BIS-(NF2) ADDUCT OF THE ACETOXY-1,3-BUTADIENE, REACTING THE RESULTING BIS-(NF2) ADDUCT OF THE ACETOXYBUTADIENE WITH A FRESH CHARGE OF N2F4 AT A TEMPERATURE IN THE RANGE OF 50* TO 250*C. UNDER SUPERATMOSPHERIC PRESSURE IN THE PRESENCE OF AN INERT HALOCARBON DILUENT TO CONVERT THE BIS-(NF2) ADDUCT TO TETRAKIS-(NF2)-BUTYLACETATE PRODUCT, AND RECOVERING SAID PRODUCT. 